Blu-Mol Xtreme quick core hole saw system/patented technology allows the operator to engage the quick release arbor to expose the unique open back design/allows for quick and easy core removal with no extra tools needed. Aggressive 10 degree positive tooth angle promotes faster and smoother cuts. M42 bimetal construction for cutting wood, metal, plastic, and stainless steel. Change out hole saw sizes fast with no extra tools needed. Available in 28 sizes, 7 and 13 piece sets.